A US Supertanker, considered the largest firefighting aircraft in the world, joined the operation on Saturday.

Palestinian authorities sent 41 firefighters and eight trucks on Friday to help in Haifa and the Jerusalem area. They returned to the West Bank late Saturday.

Israel's Nature and Parks Authority said tens of thousands of hectares of forest and shrubland had burned.

Fires in Palestinian areas of the West Bank were also extinguished by Saturday night, with the Ramallah-based Civil Defence saying it had dealt with 143 blazes which burned crops and trees but caused no casualties.

Israel's right-wing politicians have spoken out harshly in response to suspicions of arson.

At Halamish on Sunday, Education Minister Naftali Bennett said that "the person who threw the firebomb -- which was found -- that lit the fire here tried to murder the residents of an entire settlement, no less".

Dozens of olive trees near the Palestinian village of Deir Nizam near Halamish were also destroyed, and five Palestinian villages were without electricity overnight, residents told AFP.